I am attempting to work with data with a few of normal distributions mixed in with each other. What I am thinking is splitting up the data in to the separate distributions and then calculating the standard deviation of each.

The problem that I am running into is that I can not find an effective way to split the numbers up into different groups. I am also wondering if this is even the best way to go about determining if a number belongs in a set of numbers when there is more than one normal distribution.